Conodonts, a large group of tiny extinct marine animals ranging in age from the Late Cambrian to Late Triassic (ca. 500 to 200 Mya), are usually considered as jawless vertebrates. Their only commonly occurring fossilized remains are minute, phosphatic, teeth−like elements of their feeding apparatuses. In most of the early conodonts the elements were conical and strongly elongated. Many of them are characterized by possession of a deep, longitudinal groove, usually associated with sharp edges or ridges. A comparative study of the grooved elements and venomous teeth and spines of living and extinct vertebrates strongly suggests that the groove in conodonts was also used for delivery of venom. Structural convergence of the conodont apparatus Panderodus with the grasping apparatus of chaetognaths, a group of extant, venomous invertebrate predators of similarly ancient origin, provides additional support for this conclusion.
The determination of uranium isotopes in different components of the Southern Baltic (sediments, soil, birds, river) is presented and discussed in this paper. The Baltic Sea is one of the most polluted water regions in the world. On the basis of the studies was found that the most important process of uranium geochemical migration in the Southern Baltic Sea ecosystem is the sedimentation of suspended material and the vertical diffusion from sediments into the bottom water. Considerable amounts of uranium isotopes are introduced into the Baltic waters together with annual inflows of saline and well-aerated waters from the North Sea. Also very high uranium concentrations are the result of weathering and erosional processes of the rocks (e.g. Sudetic rocks) which contain elevated natural concentrations of this radionuclide. Considerable amounts of uranium isotopes are introduced into the Baltic waters together with annual inflows from the Vistula and Oder rivers, also from saline and well-aerated waters from the North Sea. The results of many our studies confirm the significant role of human activities and phosphogypsum stockpile in Wiślinka as a source of these isotopes in southern Baltic.
An earlier hypothesis concerning the origin of chaetognaths from protoconodonts found additional support in new discoveries and in recent structural, chemical and molecular investigations. The new findings show that the head armature of protoconodonts was composed not only of grasping spines but also of much smaller spicules corresponding in size and shape to the chaetognath teeth. Grasping spines of protoconodonts were originally built mainly of an organic substance. Their original composition was changed by secondary phosphatisation. The thickest layer of the protoconodont spines was originally constructed of organic fibrils, similar to those in the corresponding layer of chaetognaths. Recent molecular investigations show that the chaetognath lineage separated in the early stage of metazoan radiation, which fits the presented hypothesis. Described are some previously unknown structural details of chaetognath grasping spines, including composition of the outer layer and the origin of their distinctive tips.
The muscles and internal organs of marine animals contain many proteases. These enzymes fulfill different metabolic functions in the living organisms and affect the sensory quality and functional properties of the catch. Their activity depends on the species, life cycle, and the feeding status of the organism. Many proteases of marine origin differ from their counterparts in terrestrial animals in being more active at lower temperature and less resistant to thermal denaturation. Of practical importance in the industry is their role in ripening of salted fish, fish sauces and marinades, modyfying fish protein concentrates, ensilaging of seafood offal, and deskinning of fishery products. The negative effects comprise mainly the early post morten quality degradation of the catch and deterioration of the rheological properties of fish gels. Proteolytic preparations form different marine sources may be used successfully in food processing and as industrial enzymes, e. g. tanning agents.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.